An alternate approach to modeling of cryogenic heat exchangers

Heat exchangers used in mixed refrigerant cryogenic systems (ΔTglide > 150 K) require special attention while modeling, as the conventional simulation methods fail to account for property variations along the heat exchanger and secondary effects. High-effectiveness multiple tubes in tube heat exchangers are extensively used in Mixed Refrigerant Joule Thomson cryocoolers operating with Nitrogen-Hydrocarbon mixtures for very low-temperature applications (Typically 90 K) such as electronics cooling in large telescopes and Vacuum traps in electronics manufacturing.

An alternate 1D-heat exchanger Modeling technique using enthalpy-based equations for hot fluid and cold fluid, considering the property variation, axial conduction, heat leak, and two- phase pressure drop, has been presented in this work using the Finite difference method, and the results have been validated against the published data in the literature. Also, the total charge present in the heat exchanger has been estimated using different void fraction models present in the literature, and a comparison of the same has been presented in this work.